Turbo-Compression Cooling

SHANE GARLAND, JOHN SIMON, ALEX GRAUBERGER, DEREK YOUNG

PAST: ACHYUT PAUDEL, TORBEN GRUMSTRUP

In thermoelectric power generation, only about 40% of the energy in the fuel is converted into electricity. In other words, the power plant operates at about 40% efficiency. The remainder of the energy is converted to low-grade waste heat that must be removed to maintain the power plant's efficiency. Most power plants use water from nearby rivers, lakes, or the ocean for cooling. The water may pass directly over tubes containing the plant's heated condenser water, and then be returned, warmer, to the original source, or it may be evaporated to carry off the heat in water vapor. In areas with limited water or under drought conditions, dry-cooling systems use air to remove heat from the plant's condenser water. However, present dry-cooling technology reduces the power plant's efficiency and requires costly equipment. With water supplies becoming increasingly strained in many areas, economical dry-cooling approaches that do not reduce the efficiency of power plans are critically needed. Innovative methods to allow cooling below the daytime ambient air temperature and improve heat exchange between air and the plant's recirculating condenser water will provide the keys to ensuring the continued efficiency of power generation while decreasing the burden on water supplies.

The team will develop a thermally powered supplemental cooling system for thermoelectric power plants that will enable dry cooling. The technology features a transformational turbo-compressor and low-cost, high-performance heat exchangers that are currently mass produced for the HVAC industry. To operate, low-grade waste heat from the power plant combustion exhaust gases, or flue gas, is captured and used to power a highly efficient turbo-compressor system. The compressor pressurizes vapor in a refrigeration cycle to remove up to 30% of the power plant cooling load. The cooling system utilizes proprietary technology to maximize the turbo compressor and total system efficiencies, enabling a low production cost and an overall smaller, less expensive dry-cooling system. As a result, the cooling system could allow thermoelectric power plants to maintain a high efficiency while eliminating the use of local water resources. Furthermore, due to its very high performance, the turbo-compression cooling system has potential applications in a range of other markets, including commercial HVAC systems, data center cooling, and distributed cooling industries.